There has been much debate over the last week as to how the forthcoming Windows Server 2008 release from Microsoft will embrace Linux, specifically with regard to the interoperability between Windows and Linux as evidenced by Release Candidate 1 code.

The two sides of the story seem to be either:

Windows Server 2008 Hyper-V Beta is built upon Xen source code, a project partially funded by Microsoft, so Linux interoperability is a given. Xen will be a core part of Hyper-V, and when you run a Linux Virtual Machine calls to Xen will be translated into Hyper-V hypercalls. Hyper-V is integrated at the service level in Windows Server 2008 rather than being a hosted platform, ipso facto Linux interoperability gets the edge and VMware gets edged out on the back of this value for money equation.


Hyper-V has an architecture that bears more of a resemblance to Xen than it does to something like ESX Server for example. Xen itself runs as a guest within the parent partition, nothing more and nothing less, and certainly any suggestion that there is a similarity between the Linux kernel paravirtualisation for Xen and Hyper-V is wishful but blinkered thinking.

At the end of the day the question that needs to be asked is whether anyone seriously believes that Microsoft would stuff some open source code within the Windows kernel?

The clever money would say not on your nelly.

ms should make a distro and sell support and price out redhat and novell

well, if ESX goes open source, and provides a community edition, like, for instance Zimbra does, and stops being so secretive - microsoft will go down in the virtualization market for good. that is the problem with vmware - the server software is very hcl strict and even more closed-source than windows.

This "article" is so narrow-minded it's not even funny. When the author says "VMware gets edged out on the back of this value for money equation" he has obviously no clue what he's talking about.

VMware can't sell ESX fast enough. The demand from the enterprise is just unbelievable. And now, VMware is releasing the GA for ESX 3i, the 32 MB pure hypervisor with no console OS, being shipped out of the box for embedded systems.

So this whole thing is about what philosophy will the market accept. Xen and MS push for the hypervisor to be part of the OS, one way or another. VMware believes the hypervisor should be a separate layer, just like in the mainframe, and the OSs should get more specialized with less hardware support (not necessary in a virtual environment) and better support for the application layer. This model will help develop the Virtual Appliance market which is already taking off. Look at BEA's LiquidVM java appliance for example. Awesome project.

In regards to the hypercalls comments, the author seems to forget that VMware does support paravirtualization also. It's called VMI (Virtual Machine Interface) and is based in paravirt_ops, standard in any Linux kernel over 2.6.22. The best part, it requires NO modification whatsoever. The same binaries that boot on physical hardware will "auto-adjust" on top of a VMI-compatible hypervisor. No need for two binary versions as you do with Xen. That is the preferred model for distros, as they have to worry about a single kernel to maintain.

Of course there will be competition in the virtualization market (yes, it's a market, even in MS doesn't like it) and that is good for everybody.

Disclaimer: I work for VMware but I do not speak for the company. I'm just an engineer, but I DO KNOW what I'm talking about.